270 research outputs found

    The Slottsmøya marine reptile Lagerstätte: depositional environments, taphonomy and diagenesis

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    The Late Jurassic Slottsmøya Member Lagerstätte on Spitsbergen offers a unique opportunity to study the relationships between vertebrate fossil preservation, invertebrate occurrences and depositional environment. In this study, 21 plesiosaurian and 17 ichthyosaur specimens are described with respect to articulation, landing mode, preservation, and possible predation and scavenging. The stratigraphic distribution of marine reptiles in the Slottsmøya Member is analysed, and a correlation between high total organic content, low oxygen levels, few benthic invertebrates and optimal reptile preservation is observed. A new model for 3D preservation of vertebrates in highly compacted organic shales is explained

    Cross-sectional study of morbidity, morbidity-associated factors and cost of treatment in Ngaoundere, Cameroon, with implications for health policy in developing countries and development assistance policy

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    BACKGROUND: In a population-based epidemiological study in Ngaoundere, Cameroon, we studied cross-sectional child morbidity and the cost of necessary investigation and treatment. METHODS: Three teams of two to three health workers visited haphazardly selected households in all major housing quarters. We asked permission to enter for a health survey. Children with cough, fever or weight loss as well as sick adults were offered free-of-charge local hospital examination and treatment. RESULTS: From 177 households with 1777 persons, 51 (2.9%) persons were referred. Thirty-five of them had an undiagnosed disease threatening individual health and in many cases also public health. Seven were hospitalised, including three adults with tuberculosis. Malnutrition was diagnosed in nine small children. Four patients had AIDS, seven had malaria. Average total cost for ambulant patients was 15 USD, for hospitalised patients 110 USD. In the households, almost half of the women 16–50 years of age had no schooling. Two per cent of women and nine per cent of men were daily smokers. Coughing children were more likely than non-coughing children to live in a household with at least one smoker (OR = 3.58, 95% CI 1.72 to 7.46), and they generally lived in more poor households (P = 0.018). Twelve of 16 children with weight loss were referred from households with a high poverty score. CONCLUSIONS: Adult smoking and poverty affect children's health. The cost of hospitalisation or long-lasting therapy is beyond the means of most ordinary families. Diseases with severe consequences for public health, like tuberculosis, AIDS and malaria should have national programs with free, decentralised examination and treatment. Access to generic drugs is important. A major educational effort is needed to improve public health

    Synthesis and Characterization of Rutile TiO2Nanopowders Doped with Iron Ions

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    Titanium dioxide nanopowders doped with different amounts of Fe ions were prepared by coprecipitation method. Obtained materials were characterized by structural (XRD), morphological (TEM and SEM), optical (UV/vis reflection and photoluminescence, and Raman), and analytical techniques (XPS and ICP-OES). XRD analysis revealed rutile crystalline phase for doped and undoped titanium dioxide obtained in the same manner. Diameter of the particles was 5–7 nm. The presence of iron ions was confirmed by XPS and ICP-OES. Doping process moved absorption threshold of TiO2into visible spectrum range. Photocatalytic activity was also checked. Doped nanopowders showed normal and up-converted photoluminescence

    Variation, variability, and the origin of the avian endocranium:Insights from the anatomy of alioramus altai (theropoda: Tyrannosauroidea)

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    The internal braincase anatomy of the holotype of Alioramus altai, a relatively small-bodied tyrannosauroid from the Late Cretaceous of Mongolia, was studied using high-resolution computed tomography. A number of derived characters strengthen the diagnosis of this taxon as both a tyrannosauroid and a unique, new species (e.g., endocranial position of the gasserian ganglion, internal ramification of the facial nerve). Also present are features intermediate between the basal theropod and avialan conditions that optimize as the ancestral condition for Coelurosauria--a diverse group of derived theropods that includes modern birds. The expression of several primitive theropod features as derived character states within Tyrannosauroidea establishes previously unrecognized evolutionary complexity and morphological plasticity at the base of Coelurosauria. It also demonstrates the critical role heterochrony may have played in driving patterns of endocranial variability within the group and potentially reveals stages in the evolution of neuroanatomical development that could not be inferred based solely on developmental observations of the major archosaurian crown clades. We discuss the integration of paleontology with variability studies, especially as applied to the nature of morphological transformations along the phylogenetically long branches that tend to separate the crown clades of major vertebrate groups

    Complete Primate Skeleton from the Middle Eocene of Messel in Germany: Morphology and Paleobiology

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    The best European locality for complete Eocene mammal skeletons is Grube Messel, near Darmstadt, Germany. Although the site was surrounded by a para-tropical rain forest in the Eocene, primates are remarkably rare there, and only eight fragmentary specimens were known until now. Messel has now yielded a full primate skeleton. The specimen has an unusual history: it was privately collected and sold in two parts, with only the lesser part previously known. The second part, which has just come to light, shows the skeleton to be the most complete primate known in the fossil record.We describe the morphology and investigate the paleobiology of the skeleton. The specimen is described as Darwinius masillae n.gen. n.sp. belonging to the Cercamoniinae. Because the skeleton is lightly crushed and bones cannot be handled individually, imaging studies are of particular importance. Skull radiography shows a host of teeth developing within the juvenile face. Investigation of growth and proportion suggest that the individual was a weaned and independent-feeding female that died in her first year of life, and might have attained a body weight of 650-900 g had she lived to adulthood. She was an agile, nail-bearing, generalized arboreal quadruped living above the floor of the Messel rain forest.Darwinius masillae represents the most complete fossil primate ever found, including both skeleton, soft body outline and contents of the digestive tract. Study of all these features allows a fairly complete reconstruction of life history, locomotion, and diet. Any future study of Eocene-Oligocene primates should benefit from information preserved in the Darwinius holotype. Of particular importance to phylogenetic studies, the absence of a toilet claw and a toothcomb demonstrates that Darwinius masillae is not simply a fossil lemur, but part of a larger group of primates, Adapoidea, representative of the early haplorhine diversification

    Review of the anatase to rutile phase transformation

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